The leaflets are often found detached, and in many instances, though completely carbonized, are so firm, and so slightly attached to the shale, that they may be separated by a pair of forceps: when removed, their impression remains on the stone, as is shown in the light-coloured part of the figure 2; the form and distribution of the rib, and nervures or veins, are seen in fig. 3. From Elsecar colliery. [Illustration: Plate XXIX.] PLATE XXIX. "Trifoliate Sphenopterite." (_Sphenopteris trifoliata_, Brongniart, Hist. Veg. Foss. tab. 53, fig. 3. _Filicites trifoliatus_, of Artis. _Cheilanthites_; from its supposed analogy to the recent genus _Cheilanthes_. Göppert. _Trans. Academy of Bonn_.) This is a rare species of fern from the coal shale of Yorkshire, Elsecar Colliery. It has the leaf or frond tripinnate; the pinnæ, lobes, or wings, alternate with an odd one; the leaflets are ternate, with roundish, convex lobes. This plant has been referred to the tropical ferns, and is nearly allied to the genera _Davallia_, or _Cheilanthes_; but from the almost general absence of the organs of fructification in fossil ferns, it is impossible to refer them with any certainty to living genera. It belongs to the Sphenopteres, or wedge-shaped-leaf ferns, of M. Brongniart. A, shows the cast or matrix of the under side of the leaf; B, the upper side in relief. [Illustration: Plate XXX.] PLATE XXX. "Milton Filicite." (_Pecopteris Miltoni_, Brongniart, Hist. Veg. Foss. tab. 114, _Filicites Miltoni_, Artis.) This exquisite specimen exhibits part of two leaves attached to the stem, the under surface of the fronds, on which the fructification is beautifully displayed, being exposed. The frond is tripinnate, the stipes large and strong, the leaflets linear with the tip rounded. The fructification is arranged in lines near the margin; but slight traces of the venation of the leaflets are distinguishable. From Milton, in Yorkshire. [Illustration: Plate XXXI.] PLATE XXXI. "Plumose Pecopterite." (_Pecopteris plumosa_, Brongniart, Hist. Veg. Foss. tab. 121. _Filicites plumosus_, Artis.) This elegant fern is characterized by the plumose or wavy character of the stipes or stems of the fronds, which are tripinnate; the leaflets are lanceolate and sessile,--that is, are closely attached by their base, without a stalk. The fructification is seen disposed near the margins of the leaflets on the left hand upper part of the specimen. From the same locality as the last. [Illustration: Plate XXXII.] PLATE XXXII. "Decurrent Filicite." (_Alethopteris decurrens_, of Göppert. _Pecopteris heterophylla_, Lindley and Hutton, tab. 38. _Filicites decurrens_, of Artis.) The drawing represents but a small portion of the specimen, which indicated a plant of gigantic size.